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  1. #1
    Join Date
    Mar 2005
    Location
    Portland
    Posts
    177

    retrofitting 416A

    first day on the new job and i went with the service manager to remove hotshot from a medium temp system and retrofit 416A in it's place. all went smooth and we started with 14 lbs of 416A which is same amount of hotshot we removed. started up system and pressures seemed ok but superheat was really low (3-4 degrees) system has 3 seperate TXV's. we let it run that way long enough to bring box temp close to setpoint and then checked sight glass again.. nearly empty. added 2 lbs more since the system has a 20+ lb receiver and rechecked sight glas.. same as before and super heat unchanged.. went in and checked super heat at each seperate TXV and attempted to adjust for correct operation..heres where it gets weird.. the TXv's would either be wide open or shut.. no modulation in between. one moment my suction line leaving the evap would be 39.0 degrees and then next it was dropping like a rock to 23 degrees. all three of the txv's acted like this and adjusting made no difference. box temp was 39.0 the txv's are alco and are 25+ years old. suction pressure was 16 when box was at 37 degrees and head pressure held steady at 100 with headmaster doing it's job.*Note when the TXV's were not feeding the sight glass would nearly clear up.. this is only the second time i have worked with 416A and i had the same issue before. wondering if theres a trick to it that we werent aware of.
    Last edited by heatermanbob; 01-23-2007 at 10:13 PM.
    you will attract more flies with honey than with vinegar, but you can attract the most with a dead cat

  2. #2
    Join Date
    Jan 2006
    Location
    Near Atlanta, GA.
    Posts
    14,531
    Every time I use 416 in an R-12 system I have to close the TXVs down a lot. Cools well once you get them adjusted.

    I think you're getting flash gas to the TXVs because you don't have a steady flow of liquid to them. Add more refrigerant and clear the glass, then try and adjust SH. 416 runs such low head you may have trouble keeping the head up enough to make the Headmaster work right.

    Personally I like R-409 better for med temp and it usually requires little or no TXV adjustment.

  3. #3
    Join Date
    Sep 2001
    Location
    prov.r.i.
    Posts
    1,441
    416a runs at lower pressures,and lower temps,there is a pt chart out there for it.
    if at first you dont succeed,then skydiving is not for you

  4. #4
    Join Date
    Mar 2005
    Location
    Portland
    Posts
    177
    it only runs lower pressure and temp to about 55psi and then it's very close to R-12 I have a pt chart for the 416 and was using it.
    you will attract more flies with honey than with vinegar, but you can attract the most with a dead cat

  5. #5
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    Quote Originally Posted by k_fridge View Post
    Personally I like R-409 better for med temp and it usually requires little or no TXV adjustment.

    i will second that!



    .

  6. #6
    Join Date
    Mar 2005
    Location
    Portland
    Posts
    177
    I have used 409A many times and have great success with it but the new company preffers the 416A so thats what i have to use.
    you will attract more flies with honey than with vinegar, but you can attract the most with a dead cat

  7. #7
    Join Date
    Feb 2004
    Location
    Medford Oregon
    Posts
    807
    curius, why was the retrofit done, what was your problem. switching a gas to solve a problem never works.

  8. #8
    Join Date
    Dec 2006
    Location
    In a Mess
    Posts
    1,008
    Quote Originally Posted by heatermanbob View Post
    I have used 409A many times and have great success with it but the new company preffers the 416A so thats what i have to use.
    I was in the same position, i used to use 414b with my last company now the company i am with now used 409a so that's what I have in my van

    also i was gonna post what rocket said before i read it, why'd ya switch??

    -Mike
    Sig removed by mod. G-Rated site

  9. #9
    Join Date
    Mar 2005
    Location
    Portland
    Posts
    177
    we had a low charge situation and switched when we repaired the leak, old refrigerant was R12.
    you will attract more flies with honey than with vinegar, but you can attract the most with a dead cat

  10. #10
    Join Date
    Jan 2006
    Location
    Near Atlanta, GA.
    Posts
    14,531
    Based on my experience with 416, the first thing I'd do is close off all the expansion valves about 1.5 turns. Then clear the glass and get the box close to temp. You'll need to check the SH at each TXV and adjust until the Sh is about 8* at the coils. If the site glass gets bubbles, clear it again. You'll not get an accurate SH reading until you have a full column of liquid at the TXVs. Once you have the SH at all three coils in line, check SH at the compressor to insure that it's in the 20*-30* range.

    Make sure the system is dry, if in doubt change the drier again.

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